Alan Snyder has reported a non-reproducible crash.  The crash report is attached.
He says:
I thought I would pass this on in case it is of interest. It is not repeatable. It is on a recent personal build of JDK 9.
Current CompileTask:
C2: 327682 6561       4       javax.swing.JComponent::setEnabled (29 bytes)
Stack: [0x0000000129eb4000,0x0000000129fb4000],  sp=0x0000000129fb1b80,  free space=1014k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.dylib+0xbca6f3]  VMError::report_and_die(int, char const*, char const*, __va_list_tag*, Thread*, unsigned char*, void*, void*, char const*, int, unsigned long)+0x425
V  [libjvm.dylib+0xbcaeb6]  VMError::report_and_die(Thread*, char const*, int, char const*, char const*, __va_list_tag*)+0x4a
V  [libjvm.dylib+0x47bebb]  report_vm_error(char const*, int, char const*, char const*, ...)+0xcd
V  [libjvm.dylib+0x354e52]  ciEnv::validate_compile_task_dependencies(ciMethod*)+0x1b8
V  [libjvm.dylib+0x355564]  ciEnv::register_method(ciMethod*, int, CodeOffsets*, int, CodeBuffer*, int, OopMapSet*, ExceptionHandlerTable*, ImplicitExceptionTable*, AbstractCompiler*, bool, bool, RTMState)+0x6da
V  [libjvm.dylib+0x41bf32]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0xe32
V  [libjvm.dylib+0x41e993]  Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool, DirectiveSet*)+0x31
V  [libjvm.dylib+0x322ba5]  C2Compiler::compile_method(ciEnv*, ciMethod*, int, DirectiveSet*)+0x139
V  [libjvm.dylib+0x42f01f]  CompileBroker::invoke_compiler_on_method(CompileTask*)+0x7bb
V  [libjvm.dylib+0x42e528]  CompileBroker::compiler_thread_loop()+0x2e0
V  [libjvm.dylib+0xb61804]  JavaThread::thread_main_inner()+0x1f6
V  [libjvm.dylib+0xb6144a]  JavaThread::run()+0x3cc
V  [libjvm.dylib+0x9cdb02]  thread_native_entry(Thread*)+0x12b
C  [libsystem_pthread.dylib+0x405a]  _pthread_body+0x83
C  [libsystem_pthread.dylib+0x3fd7]  _pthread_body+0x0
C  [libsystem_pthread.dylib+0x13ed]  thread_start+0xd